As described in German Pat. Nos. 2,435,498 and 2,550,770, the stroke length of reciprocating members, e.g., tool carriers, of conventional machining assemblies is controlled by a computing circuit which receives, in the form of electrical signals, measurements of machining parameters such as initial switching delays, temperature changes, oil viscosity and variations in stroke velocity, as well as load and power source output, which might affect the precision of the machining process. The computer calculates or predicts the effect of the parameters' values on the motion of the reciprocating machining member and modifies that motion to compensate for the predicted effects.
One disadvantage of such a stroke length control system is the complexity and expense inherent in providing separate detectors for each parameter being monitored. Moreover, the accuracy of the stroke reversal control can occasionally be seriously impaired when mistakes in the measurements of several parameters combine to cause a single large error in the determination of a reversal point.